Tamoxifen attaches to the hormone receptor in the cancer cell, blocking estrogen from attaching to the receptor.

This slows or stops the growth of the tumor by preventing the cancer cells from getting the hormones they need to grow.

Tamoxifen is the generic form of the brand-name drug Soltamox, which is used to treat some types of breast cancer in men and women.

Tamoxifen is prescribed to treat metastatic breast cancer, or cancer that has spread to other parts of the body. Tamoxifen is also used to lower the chance of breast cancer in high-risk women (for example, those with a family history of breast cancer).

Tamoxifen Dosing

Usual Adult Dose for Breast Cancer:

For the treatment of metastatic breast cancer in women and men:

20 to 40 mg orally Dosages greater than 20 mg should be given in divided doses (morning and evening).

For the treatment of women with Ductal Carcinoma in Situ, following breast surgery and radiation:

20 mg orally daily for 5 years.

To reduce the incidence of breast cancer in women at high risk for breast cancer:

20 mg orally daily for 5 years.

Usual Adult Dose for Breast Cancer - Adjuvant:

For the treatment of node-positive breast cancer in postmenopausal women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation:

10 mg orally 2 to 3 times a day for 5 years.

Usual Adult Dose for Breast Cancer - Palliative:

10 to 20 mg orally twice a day

A beneficial response may not be evident for several months after initiation of therapy.

Usual Pediatric Dose for McCune-Albright Syndrome:

For use in girls age 2 to 10 years with McCune-Albright Syndrome and precocious puberty:

20 mg once a day. The duration of treatment is up to 12 months.

Usual Pediatric Dose for Precocious Puberty:

For use in girls age 2 to 10 years with McCune-Albright Syndrome and precocious puberty:

20 mg once a day. The duration of treatment is up to 12 months.

Tamoxifen Can:

reduce the risk of breast cancer coming back by 40% to 50% in postmenopausal women and by 30% to 50% in premenopausal women

reduce the risk of a new cancer developing in the other breast by about 50%

shrink large, hormone-receptor-positive breast cancers before surgery

slow or stop the growth or advanced (metastatic) hormone-receptor-positive breast cancer in both pre- and postmenopausal women

lower breast cancer risk in women who have a higher-than-average risk of disease but have not been diagnosed

Tamoxifen offers other health benefits that aren't related to treating cancer. Because it's a SERM, it selectively either blocks or activates estrogen's action on specific cells. While tamoxifen blocks estrogen's action on breast cells, it activates estrogen's action in bone and liver cells. So tamoxifen can: